The present invention relates to a press system for forming shaped articles, e.g. pellets presses or tablets presses and more particularly, although not exclusively, to a press system for use in producing tablets or pellets, which could be used in pharmaceutical, nutritional, chemical and other industries.
The terminology of tablets or pellets in this application is not limited to the oral taking medicine, it also includes the pellets of small rod-shaped or ovoid mass, as of compressed steroid hormones, intended for subcutaneous implantation in body tissue to provide time release over an extended period of time (Source: The American Heritage Stedman's Medical Dictionary). These pellets are surgically inserted under the skin of patients and are time released over a period of time, eliminating the need to take medication orally, through injection or topically on a daily basis. Patients that require Hormone Replacement Therapy, Diabetics requiring insulin, or individuals that want vitamins and minerals will benefit from the use of these pellets. And therefore it is of great importance that our invention accomplishes the manufacture of these pellets in great accuracy and repeatability to ensure no harm is incurred by the individual. The small diameter, hardness, dissolution rate and friability to manufacture pellets can not achieved by the traditional tablet or pellets making machines.
Right now, the large-scale production of tablets or pellets typically involves the use of tablet punches which operate to compact a volume of powder filled in a die. The powder in the die is held between opposing punches which move together by a predetermined distance of travel to produce a tablet of controlled thickness within a die of known geometry. This is such that the formed tablet has a known or determinable density according to the die geometry and volume of powder used but there is no direct control of the force applied to the powder during the filling process.
It is because the pellets press machines in the prior art, such as US 2009/0130243 A1 or WO 2014/001805, rely on gravity feed only or a combination of gravity feed and fan feed blades to the dies. These methods of feeding do not allow the use of dense or sticky powders to be used. These powders will not flow downwards into the dies because they bind together and need an external force to force them into the dies. No downward force is produced by the fan blades and their purpose is to control the rate at which the dies are filled. To allow powders to flow in the prior art an excipient needs to be added, this can cause a change in powder formulation with undesirable results and therefore not allow new formulas or natural ingredients to be used as powder.
Even though a pellet molding apparatus, as in U.S. Pat. No. 4,317,649, have an auger filler to fill die holes. But because of the auger distance away from the die holes, the auger only acts as a switch to allow the flow of powder or stop the flow of powder. Gravity is still the force used in filling the die holes because the powder falls from the auger location down the tube then into the dies.
The prior art has a limitation of only filling large diameter of die size holes accurately. It is also because there is no force used for filling the dies, the hardness or accuracy of dose of the pellets can not meet the requirement to be used as a subcutaneous implantation in body tissue.
In view of the preceding, it would therefore be advantageous to have a press machine that can use dense and sticky powder to produce small diameter, hardness, dissolution rate pellets of outstanding accuracy, which can be surgically inserted under the skin of patients and be time released over a period of time.